/*=====================================================================*
 *                   Copyright (C) 2011 Paul Mineiro                   *
 * All rights reserved.                                                *
 *                                                                     *
 * Redistribution and use in source and binary forms, with             *
 * or without modification, are permitted provided that the            *
 * following conditions are met:                                       *
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 *     * Redistributions of source code must retain the                *
 *     above copyright notice, this list of conditions and             *
 *     the following disclaimer.                                       *
 *                                                                     *
 *     * Redistributions in binary form must reproduce the             *
 *     above copyright notice, this list of conditions and             *
 *     the following disclaimer in the documentation and/or            *
 *     other materials provided with the distribution.                 *
 *                                                                     *
 *     * Neither the name of Paul Mineiro nor the names                *
 *     of other contributors may be used to endorse or promote         *
 *     products derived from this software without specific            *
 *     prior written permission.                                       *
 *                                                                     *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND              *
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,         *
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES               *
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE             *
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER               *
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,                 *
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES            *
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE           *
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR                *
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 * Contact: Paul Mineiro <paul@mineiro.com>                            *
 *=====================================================================*/

#include "estep.h"
#include "prating.c"
#include "normalize.c"

static const float log1mepsilon = -0.000010000050000333336;/* log (0.99999) */
static const float logepsilon = -11.512925464970228;       /* log (0.00001) */

float
estep (const float*             alpha,
       unsigned int             n_labels,
       float                    logbeta,
       float*                   pz,
       const float*             logpriorz,
       int                      clamp,
       const Rating*            ratings,
       unsigned int             n_ratings,
       int                      symmetric)
{
  if (clamp < 0 || clamp >= (int) n_labels || n_labels < 2)
    {
      for (unsigned int i = 0; i < n_labels; ++i)
        {
          pz[i] = logpriorz[i];
        }
    }
  else
    {
      float log_n_labels_m1 = fastlog (n_labels - 1);

      for (unsigned int i = 0; i < n_labels; ++i)
        {
          pz[i] = logepsilon - log_n_labels_m1;
        }

      pz[clamp] = log1mepsilon;
    }

  for (unsigned int i = 0; i < n_ratings; ++i)
    {
      for (unsigned int j = 0; j < n_labels; ++j)
        {
          float dlogbetatmp;
          float ddlogbetatmp;

#define alphafunc(_k)                                           \
  ({                                                            \
    (_k == j) ? -1.0 :                                          \
    (symmetric && _k < j)                                       \
        ? alpha[ratings[i].worker * n_labels * n_labels +       \
                _k * n_labels +                                 \
                j]                                              \
        : alpha[ratings[i].worker * n_labels * n_labels +       \
                j * n_labels +                                  \
                _k];                                            \
  })

          pz[j] += logprating (ratings[i].rating,
                               alphafunc,
                               logbeta,
                               dlogbetatmp,
                               ddlogbetatmp,
                               n_labels);
#undef alphafunc
        }
    }

  return safe_exponentiate_normalize (pz, n_labels);
}
